Possible Bug - My material color won't change
You must have deleted something from the original node network.

Your color ramp is not driven by any coordinate based texture so you will only get a solid color (assuming the same color at every point on the sphere). Since your ramp is a gradient of grey and you are mixing it 50% with black, you end up with a middle grey solid diffuse color! No surprise there!

To see the effect of the ramp, simply add a texture that's based on some sort of coordinates for example a Musgrave Texture, a Noise Texture or a Voronoi Texture would do. So would an Image Texture...